Add api_go_grpc rules for metrics_service, als, and trace_service.
To support those changes, also added the necessary go_proto_library
rules in the repositories.bzl definitions for prometheus_metrics_model,
and io_opencensus_trace, and augmented the go_build_test.go to
verify these changes were correct.
Signed-off-by: William Chang <mr.williamchang@gmail.com>
Mirrored from https://github.com/envoyproxy/envoy @ fb7797fd7df696cd239cc1d3792719361b62c684